In a game cartridge, competitive people spend (loads of) time breeding for specific IVs just for a specific Hidden Power type. Simulators have more freedom, since the IVs can be manipulated more easily.

To add, 'mons with very shallow movepools (like Jolteon or Lilligant) use Hidden Power as a coverage move to hit opponents that would resist their STABs. Some 'mons use Hidden Power to hit specific threats (like Ice for Dragonite/Salamence/Gliscor or Grass for Gastrodon on Heatran).